From automotive technology, hybrid drive arrangements and methods for controlling and/or regulating a starting process for vehicles are known. The known hybrid drive arrangement comprises an internal combustion engine which can be coupled by way of a first clutch to an input shaft of an electric machine. The electric machine is connected, via a second clutch, to the input shaft of a variable-ratio transmission. The second clutch may also be integrated in the transmission. In addition, a control unit is provided, which controls the individual components to bring about a starting process in the vehicle.
When the combustion engine is idling, the first clutch is disengaged, the second clutch is engaged and a starting gear is engaged in the transmission, a purely electric start takes place. In these driving situations, the vehicle does not accelerate sufficiently to allow the combustion engine to be coupled by way of the first clutch, since the speed of the electric machine is too low. Possible reasons for this are that the starting resistance is too high; the electrical energy available from the energy accumulator is too little or the electric machine cannot build up sufficient torque. Thus, the combustion engine must deliver an additional torque. Since the first clutch cannot be used as a starting clutch, combustion-engine-powered starting must take place via the second clutch.
To bring about the transition to combustion-engine-powered starting, in the known method it can be provided that the starting torque at the electric machine is first reduced so as to be able to disengage the second clutch. This allows the electric machine to be coupled to the combustion engine via the first clutch. This is done by synchronizing the speeds of the electric machine and the combustion engine so that the first clutch can be engaged. In this way, starting can be carried out using the second clutch so that the torque from the combustion engine and the torque from the electric machine are combined to bring about a hybrid start via the second clutch. This, however, has the disadvantage that with the known method an interruption of the traction force takes place during the transition from electric starting to hybrid starting.
The purpose of the present invention is to propose a hybrid drive arrangement and a method for controlling and/or regulating a starting process of the type described, by way of which a transition between a purely electric start and a combustion-engine-assisted or hybrid start can take place without interruption of the traction force.